I have raced S60R last year from 40-100mph. We were dead even although I had slightly pulled about 1/8 car lengths on him. I am not sure if it was 6sp or automatic.
It's got one of the most sophisticated suspension system plus a refined interior. If it is about 300-400 lbs lighter, it would probably be the most popular sports sedan beside S4 and M3.
I usually check out swedespeed.com for information.